Scanning electron microscopes (SEMs) and scanning ion microscopes (SIMs), along with various lithography tools, utilize a focused beam of either electrons or ions to generate measured signals from a target. The beam may also be used to physically or chemically alter a target. “Target” in this context refers generally to an object or substance that is the subject of the measurement—a sample, in the case of a microscope, or a substrate, in the case of fabrication tools used for electron and ion beam lithography, as examples.
SEMs in particular provide magnified images of targets. Magnification can range from approximately 20× to over 500,000×, depending on type and sample. SEMs are a universal tool used in material science, electronics, geology, forensics, art conservation and environmental research, among other areas. Current drivers of the development of SEM technology include the desire for higher resolution (e.g. nanoscience and microelectronics) and higher throughput (e.g. microelectronics and brain cell mapping), as examples. Current systems often are run at more than 100,000× since the current node for microelectronics is 22 nm or smaller. Therefore, some way of enhancing resolution is desired. Meanwhile, other technology, such as transmission electron microscopy, may require thin samples that are impractical to prepare or very time consuming to use relative to scanning electron microscopy.